Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated Oct 29, 2026

Planting zone for Fort Knox, KY

Fort Knox, KY is in USDA zone 7a across its 2 ZIP codes. The median last spring frost is April 19 and the first fall frost October 24.

Fort Knox on the zone map

Outlined: its 1 ZIP code areas · tap the map for the zone at any spot · scroll or pinch to zoom

Not the official USDA Plant Hardiness Zone Map. Zones come from the 2023 USDA hardiness-zone data by the PRISM Group, Oregon State University; we re-mapped and recolored them. The official map is at planthardiness.ars.usda.gov.

Zone7a0 to 5 °F

ZIP codes2

Last frostApr 19

First frostOct 24

Growing season186 days

7a 2 ZIPs

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Fort Knox, KY…

Forecast data: National Weather Service (api.weather.gov), public domain. This is not a warning service — for official frost and freeze warnings see weather.gov.

Frost dates in Fort Knox, KY

JanFebMarAprMayJunJulAugSepOctNovDec

Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free

Last spring frostApril 19median — 50% chance of a later frost

Safe for tender plantsMay 2only 10% chance of frost after

First fall frostOctober 24median — 10% chance by Oct 9

Growing season186 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 6 and returns around November 2.

From the NOAA station Brandenburg, KY, elevation 617 ft. NOAA NCEI U.S. Climate Normals 1991–2020, 32 °F threshold. Low spots and valleys can freeze later in spring than the station.

When to plant vegetables in Fort Knox

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 8 – Mar 22

SpinachSow outdoors · Mar 8 – Mar 29

Broccoli, cabbageStart indoors · Feb 8 – Feb 22

Broccoli, cabbageTransplant · Mar 29 – Apr 12

Onion setsPlant outdoors · Mar 22 – Apr 5

PotatoesPlant outdoors · Mar 29 – Apr 12

LettuceSow outdoors · Mar 22 – Apr 5

Carrots, beetsSow outdoors · Mar 29 – Apr 12

TomatoesStart indoors · Feb 22 – Mar 8

TomatoesTransplant · Apr 26 – May 10

Peppers, eggplantStart indoors · Feb 8 – Feb 22

Peppers, eggplantTransplant · May 3 – May 17

BeansSow outdoors · Apr 26 – May 10

Sweet cornSow outdoors · Apr 26 – May 10

Cucumbers, squashSow outdoors · Apr 26 – May 10

Fall lettuce, spinachSow outdoors · Aug 29 – Sep 12

GarlicPlant cloves · Oct 10 – Nov 14

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 19) and first fall frost (Oct 24) with the rules of thumb U.S. extension services publish. Cool-season crops take a light frost; warm-season crops do best once the soil is above about 60 °F.

When spring arrived in 2026

In 2026, spring leaf-out near 40121 came on Mar 3 — 7 days earlier than the 1991–2020 average (Mar 10).

average
Mar 102026
Mar 3

JanFebMarAprMayJun

The Spring Index marks the day when accumulated warmth is enough for lilac and honeysuckle to leaf out — a widely used signal that the growing season has started. Source: USA National Phenology Network, www.usanpn.org — Spring Indices, first leaf, 2026 (data as of 2026-09-08) and 30-year average 1991–2020 (CC BY 4.0).

Native plants for zone 7a in Kentucky

547 plants native to the lower 48 states, recorded in Kentucky, and rated by the USDA to survive 0 °F or colder — the bottom of zone 7a. Each links to its USDA PLANTS profile.

Source: USDA, NRCS. 2026. The PLANTS Database (plants.usda.gov), National Plant Data Team — state distribution, native status and the “Temperature, Minimum” characteristic. Check light, moisture and soil needs before buying; local nurseries and your state native plant society can confirm what thrives in Fort Knox, KY.

Soil in Fort Knox, KY

The soil mapped at the center of ZIP 40121 is Vertrees — silty clay loam, well drained.

TextureSilty clay loamholds water and nutrients; slow to drain and warm up

pH5.9moderately acidic; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter1%low — add compost

Hydrologic groupCwater soaks in slowly

Farmland classNot prime farmlandUSDA classification

Map unit: Vertrees silty clay loam 6 to 20 percent slopes, severely eroded.

Soil Survey Staff, Natural Resources Conservation Service, USDA. Soil Survey Geographic (SSURGO) Database, via Soil Data Access, accessed 2026-10-29. The soil at the center point of ZIP 40121; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Fort Knox, KY

Summer high86 °Faverage high, July

Winter low23 °Faverage low, January

Hot days27days a year at 90 °F or more

Freezing nights109nights a year at 32 °F or less

Growing degree days3,851base 50 °F — the season’s usable heat

Longest day14 h 48 mindaylight on June 21

Shortest day9 h 32 mindaylight on December 21

Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully

Precipitation53.3 inper year, rain and melted snow

Average high and low, by month

Precipitation by month inches

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Brandenburg, KY (9 mi away); precipitation: Brandenburg, KY (9 mi away). Daylight is calculated from latitude.

ZIP codes in Fort Knox

Kentucky planting zones →

Questions about Fort Knox

What planting zone is Fort Knox, KY?

Fort Knox, KY is in USDA hardiness zone 7a on the 2023 map (7a: 0 to 5 °F).

When is the last frost in Fort Knox, KY?

The median last spring frost is April 19 and the median first fall frost is October 24 (NOAA 1991–2020 normals, Brandenburg station).

When can I plant a garden in Fort Knox, KY?

Cool-season crops like peas and spinach go in around Mar 8 – Mar 29; tomatoes, peppers, beans and squash after about Apr 26, once frost risk has passed.

What kind of onions grow in Fort Knox, KY?

Intermediate onions: the longest day is 14 h 48 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

How much rain and snow does Fort Knox, KY get?

About 53.3 inches of precipitation a year (NOAA 1991–2020 normals).